This invention concerns an inspection apparatus, e.g. for use in a sorting machine.
Sorting machines are known in which objects to be sorted (e.g. agricultural products such as peas and beans, and mineral products such as pieces of ore) are fed to a transparent tubular member so as to fall therethrough under gravity. The objects falling through the tubular member are illuminated from the exterior of the tubular member and are also viewed from the said exterior, whereby the illuminating means and the viewing means employed are protected by the tubular member from dust associated with the objects. In such machines, however, considerable problems have arisen from the fact that the tubular member itself has reflected light onto the viewing means so that the response of the latter did not depend solely on light reflected or transmitted by the objects, whereby sorting efficiency was impaired. Many attempts have been made to solve the problem, but such attempts have not been very successful. Thus, for example, it is not practicable to blacken the areas which create the undesirable reflections since this would produce inadequate and uneven illumination.